Flat-drill-grinding apparatus.



J. S. WINCRANTZ. PLIAT DRILL GRINDING APPARATUS.

APPLICATION FILED JUNE 10, 1914.

Patented Spt. 15, 191 1 WITNESSES ATTORNCYG .WMMM V A.

UNITED STATES PATENT OFFICE.

JOHN S. WINCRANTZ, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB TO SAMUEL NEWMAN, OF PITTSBURGH, PENNSYLVANIA.

FLAT-DRILL-GRINDIN G APPARATUS.

Specification of Letters Patent.

Patented Sept. 15, 1914.

To all whom it may concern Be it known that I, JOHN S. WINCRANTZ, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in F lat- Drill-Grinding Apparatus, of which the following is a specification.

The invention relates to apparatus for grinding the undercut at the ends of fiat drills which are. ordinarily of self-hardening steel. These drills are very expensive and must be discarded when the end is worn down so that the undercut, which gives the clearance in grinding, disappears. This occurs when only a small fraction of the drill has been used; and it is the object of my invention to' provide a grinding mechanism in which a new undercut can be ground when the drill is worn down, thus permitting the major portion of the drill to be used before it is discarded. One embodiment of the invention is illustrated in the accompanying drawings, wherein Figure 1 is a plan view of the apparatus, Fig. 2 is a side elevation of the apparatus, Figs. 3 and 4 are detail views of the clamping means for the drill, Fig. 5 is a detail view showing the relation of the end of the drill to the grinding wheel, and Fig. 6 is a section on the line VI-VI of Fig. 1.

The disk grinding'wheel 1 may be operated in any desired way, this being accomplished in the embodiment of the invention illustrated, by means of a handle 2 and gearing contained in the casing 3. The corner of this grinding wheel or disk 1 is beveled as indicated at 4, in order to secure the undercut as hereinafter described.

Mounted detachably upon the casing 3 is the supporting bracket 5, which bracket carries at its upper end the vertically swinging arm 6, such arm being stopped upon its downward movement by means of the adjustable screw 7, and on its movement in the reverse direction by the fixed stop 8. Mounted for longitudinal and rotary movement with respect to the arm 6 is the clamping member 9 for carrying the drill, such clamping member being provided with a shank 10 which fits into the arm 6. As indicated in Fig. 1, the arm 6 is split and the stem 10 is clamped against movement by means of the thumb screw 11 extending through lugs carried by the two halves of .wheel.

the split arm 6. This arrangement provides for the longitudinal and rotary adjustment of the stem 10, and the clamping member 9 carried thereby.

The upper jaw 12 of theimember 9 is provided with a thumb screw 13 threaded through the jaw 12 and swiveled at its lower end to a clamping plate 14, such clamping plate 14 being used in the position indicated in Fig. 3, with small drills, or in the position indicated in Fig. 4, with larger drills. Extending freely through the lower jaw 15 of the member 9 is the pin 16, such pin 16 being secured at its upper end to the clamping plate 17 which engages the lower side of the drill. Pin 16 is threaded and the threaded portion is engaged by the thumb screw 18, so that the plate 17 may be rigidly clamped in any desired position of rotary adjustment. The provision for clamping the plate 17 in position is a desirable one, as it is possible to release the upper plate 14 and turn the drill over for grinding its other face without having to reposition the plate 17. In this connection the use of the adjustable stop 7 is advantageous, since it serves as a gage for grinding the second face of the drill after the first face has been ground with the stop 7 as a limiting means for the downward movement of the arm. In order to position the drill longitudinally the loop 18 is provided upon the lower clamping plate 17, such loop beingclamped in position by means of a set screw (not shown) upon its lower side.

In operation, the parts are positioned as indicated in Figs. 1 and 2, with the lower face of one side of the drill at the end thereof lying over the beveled portion 4 of the Upon rotating the grinding wheel an undercut is secured upon the drill to the rear of the cutting edge 19 (Fig. 2). In other words, the metal of the face of the drill is cut out to the rear of the line 19, thus providing the necessary clearance such as is found in drills of this character when they are sent out new from the concerns producing them. This undercut is indicated at 19 of Fig. 6. The stop screw 7 regulates the amount of this clearance, and during the grinding operation the weight of the arm and the parts carried thereby secures the downward feed of the tool, the thumb screws 11, 13, and 18 being screwed tight at such time. After this grinding oppleted, the thumb screw eration upon one side of the drill is com- 13 is loosened and the drill removed and turned with the side just ground, up. During this reversing operation the back stop 18 and the lower clamping plate 17 remain securely clamped in position, so that when the drill is reversed and the thumb screw 13 moved to clamping position the drill is in exactly the right position for undercutting the portion of the upper face of the drill marked 20 (Fig. 2) and lying above the dotted line. The amount of material cut away by this second grinding operation is the same as in the first grinding operation, since the screw 7 limits the downward movement of the drill. The longitudinal and rotary adjustment of the stem 10, the swinging adjustment of the arm 6, and the longitudinal adjustment of the drill itself between the clamping plates 14 and 17, permits of the drill being brought exactly to the position desired for the securing the'kind of undercut desired, and permits the use of the apparatus with any type or size of flat drill. The invention comprehends any and all apparatus in which the corner of the grinding disk is beveled and in which the drill is held at a position of inclination such that one face thereof is engaged at the beveled portion of the wheel to permit an undercut, and the structure here shown is merely illustrative of the broad invention involved.

What. I claim is:

1. In combination in apparatus for grinding an undercut on a flat drill, a disk grinding wheel having its corner beveled, and a clamping means for holding a flat drill in-- clined downwardly and transversely of the plane of rotation of the drill so that one face thereof at the end of the drill engages the beveled portion of the wheel.

2. In combination in apparatus for grinding an undercut on a flat drill, a disk grinding wheel having its corner beveled, an arm mounted to swing vertically, and a clamping device adjustable rotatably upon said arm, and adapted to hold the drill downwardly and transversely inclined with respect to the grinding wheel with its face at the end of the drill in engagement with the beveled portion of the wheel.

3. In combination in apparatus for grinding an undercut on a flat drill, a disk grinding wheel having its corner beveled, an arm mounted to swing vertically, and a clamping device adjustable longitudinally and rotatably with respect to said arm and adapted to hold the drill downwardly and transversely inclined-with'respect to the grinding wheel with its face at the end of the drill in engagement with the beveled portion of the wheel.

4. In combination in apparatus for grind-' ing an undercut on a fiat drill, a disk grinding wheel having its corner beveled, and a clamping means for holding a flat drill comprising an arm swinging in a plane parallel to the plane of rotation of the wheel, and a holder for the drill having a stem supported for rotary adjustment on the arm and adapted to hold the drill in a position inclined obliquely with respect to the plane of rotation of the wheel and with one of the faces of the drill at its end in engage ment with the beveled portion of the wheel.

5. In combination in apparatus for grinding an undercut on a flat drill, a disk grinding wheel having its corner beveled, and an adjustable clamping means for holding a flat drill inclined obliquely with respect to the axis of rotation of the wheel and with respect to the plane of rotation of the wheel so that one face of the drill at the end there of lies over the beveled portion of the wheel.

6. In combination in apparatus for grinding an undercut on a flat drill, a disk grinding wheel having its corner beveled, and an adjustable clamping means for holding a flat drill comprising a pair of opposing jaws mounted for adjustment with respect to the wheel. a plate swiveled on one of the jaws for engaging one side of the drill, means for clamping the said plate in any desired position, a plate on the other jaw for engaging the other side of the drill and means for adjusting such last plate in and out to clamp the drill, the said clamping means being adapted to hold the drill transversely inclined with respect to the beveled edge of the wheel.

7. In combination in apparatus for grinding an undercut on a flat drill, a disk grindin g wheel having its corner beveled, and adjustable clamping means for holding a flat drill comprising a pair of relatively fixed jaws mounted for adjustment with respect to the wheel, a pair of clamping plates for engaging opposite sides of the drill, one of which is swiveled upon a clamping screw threaded through one of the jaws, and the other of which plates is mounted for rotary adjustment on the other jaw, and means for clamping the last mentioned jaw in any desired position of rotary adjustment.

In testimony whereof I have hereunto signed my name in the presence of the subscribed witnesses.

HN S. WINCRANTZ.

Witnesses:

\ ARCHWORTH MARTIN,

M. L. Jones. 

